Currently, secondary batteries that employ a general aqueous solution as an electrolyte solution are configured with a plate-like positive electrode, a separator, and a similarly plate-like negative electrode. Alkali secondary batteries are configured with an aqueous solution of potassium hydroxide, sodium hydroxide or the like containing lithium hydroxide as an electrolyte solution, whereas lead storage batteries are configured using diluted sulfuric acid.
Batteries generally have a square-type shape including a plate-like shape, and a cylinder-type shape including a coin-like shape. In the former square type batteries, positive electrodes and negative electrodes are alternately arranged with separators interposed therebetween, and these electrodes are lead out collectively, as a positive electrode terminal, and a negative electrode terminal, respectively. Many of the alkali secondary batteries are of a cylinder type, and a group of electrodes consisting of a positive electrode, a separator and a negative electrode is coiled and inserted into an electrolytic bath. The lid and the can are insulated, and each is employed as a positive electrode terminal, and a negative electrode terminal. In addition, alkali secondary batteries of the square type have also prevailed.
As electrodes in alkali secondary batteries such as nickel-cadmium batteries and nickel-hydrogen batteries which have been broadly prevailing, electrodes having a comparatively great thickness of about 0.65 to 0.8 mm are used for providing high capacity, whereas electrodes having a smaller thickness of about 0.4 to 0.6 mm are used for providing high output.
In addition, with respect to electrodes of these alkali secondary batteries, electrodes of sintered type and of foamed nickel type have been well known as positive electrodes, whereas electrodes of paste type provided by applying a paste containing an active material to an electricity collector having a secondary structure such as a punching metal, followed by compression are principally adopted as negative electrodes.
As electricity collectors of positive electrodes, those of sintered type are sintered compacts obtained by sintering nickel carbonyl on a punching metal or the like, whereas those of foamed nickel type are porous bodies obtained by nickel plating on a foamed resin, followed by removing the resin by incineration. In addition, a number of porous bodies having irregularity formed by a mechanical processing have been proposed; however, they have not developed a practical level.
As a separator in alkali secondary batteries, a nonwoven fabric made of polyamide, and a hydrophilized polyolefin based nonwoven fabric predominantly having a thickness of about 80 to 200 μm have prevailed. In lead storage batteries, a paper, porous polyolefin plate or glass fiber cloth is used, and generally, it is necessary that it is impregnated in a large amount of sulfuric acid which directly involves in a charge and discharge reaction. Thus, a porous body which is thicker than those for use in alkali secondary batteries is used.
Moreover, a fiber battery having a battery structure that is different from a group of electrodes including a conventional positive electrode, a separator and a negative electrode, and is configured using as an electricity collector a fibrous substance having electronic conductivity (carbon fiber) coated with an active material on the surface thereof was proposed (see Patent Literature 1).
In addition, a method of processing an electric apparatus for avoiding occurrence of problems of short of storage batteries, capacitors and the like was proposed in which a group of first fiber electrodes are disposed on a first layer so as to be parallel with one another and a group of second fiber electrodes are disposed on a second layer so as to be parallel with one another, and then the second layer is brought into immediately adjacent to the first layer to form an electric connection between electrodes (see Patent Literature 2).
Also, a battery was proposed which includes: a plurality of fiber anodes: a plurality of fiber cathodes; an electrolyte; a sealing case for sealing in the transverse direction of the fiber anodes, the fiber cathodes and the electrolyte; and end plates for sealing both ends of the sealing case for sealing in the transverse direction, in which the ends of the fiber anodes are extended from the end plate to protrude, and the ends of the fiber cathodes are also extended from the end plate (see Patent Literature 3). According to this battery, a battery having a large electrode surface area is easily produced; therefore, charging capacity per volume of the battery can reportedly increase.
Furthermore, a cord type battery was proposed in which: either one of electrode materials, which is a long negative electrode material or a positive electrode material, provided by forming an electrode active material on the outer periphery of each electrode is employed as a core material; another electrode material is provided concentrically on the outer periphery thereof via a polymer solid electrolyte; and these are packaged with a covering material to configure a cord shape having flexibility in its entirety (see Patent Literature 4). The configuration of this battery is basically the same as generalized Leclanche type dry cells. In other words, dry cells are provided with a positive electrode material at the center, a negative electrode material at the peripheral part, and an electrolyte therebetween to form a cylinder shape.
On the other hand, with respect to an electrolytic deposition method that is a method of filling a nickel electrode with an active material which relates to the nickel electrode of the present application, a method of filling a sintered type nickel electrode with an active material was proposed. For example, in an attempt to obtain a nickel electrode having a low reaction resistance and small polarization on the positive electrode side, which does not accompanied by lowering of the capacity in an early stage, and achieves superior reliability at high temperatures and sufficient prolonging of life duration, Patent Literature 5 discloses a nickel electrode for a battery in which a porous metal substrate such as a sintered nickel substrate is filled with nickel hydroxide obtained by an electrolytic deposition method as a part of the total amount of the active material required, and filled with nickel hydroxide obtained by a chemical impregnation method in a predominant quantity of the total amount of the active material required.